It's well-known that the transmission roller wheel mounted on container/pallet loader platform can be made into several models according to the roller structure and position relationship between the roller and drive axle: straight roller wheel, 45° pineapple type roller wheel and 90° trefoil type roller wheel. The straight roller wheel characterizes the same direction with the drive axle, and the roller contacts with the cargo supporting plate in line. The advantages for using this straight roller wheel are: simple structure, stronger force transferred, less abrasion and convenience for maintenance, while the disadvantage is that the cargoes with single degree of freedom can only be transferred longitudinally and are incapable of transferring rotationally and transversely. So it is only applicable for small lift transfer platform device. For 45° pineapple type roller wheel, rollers are divided into districts and mounted on the wheel symmetrically. The advantages for using this 45° pineapple type roller wheel are: as the roller axis makes an angle of 45° with the drive axle and the direction of resultant force (magnitude and direction) is identical with direction of cargoes rotation, cargoes may be transferred in longitudinal, transverse and rotative directions, while the disadvantages are: efficiency is reduced because the component force is 0.7 time of the resulting force during longitudinal and transverse transferring; the roller contacts with cargoes on single point, which results in more abrasion; and it is necessary to add rollers for transferring stronger force. The 90° trefoil type roller wheel can only transfer cargoes along single direction forward and backward, therefore, to realize longitudinal, transverse moving and rotation, roller wheel axles must be intercrossed in longitudinal and transverse directions. The advantages for using this 90° trefoil type roller wheel are: longitudinal and transverse moving can be controlled respectively and conveniently, while the disadvantages are: too many roller wheel axles, intercross of axles, complicated structure, difficult to arrange transferring, poor processing property, single point contact resulting in more abrasion, and axial projection of rollers outline is hardly to be continuous.